1. Field of the Invention
The present invention relates generally to a magnetic head for use in video tape recorders (VTR) and the like, and more particularly concerns the magnetic head implemented through a magnetic thin film technique and a method of manufacturing the same.
2. Description of the Prior Art
In recent years, there has been a consistent demand for a magnetic head for use in VTR or the like applications which meet the requirements of a short gap length, a narrow track width, compatibility with a high coercive tape and others for attaining a high density in the recording of data or information, and various magnetic heads have been proposed which are implemented by using magnetic thin films of soft magnetic metals such as Sendust, Permalloy and the like as the materials for the head core to fulfill the requirements mentioned above.
One of methods of forming the magnetic gap of such magnetic head is realized by resorting to a thin film technology for attaining a high precision in implementation of the magnetic gap, being different from hitherto known methods of fabricating conventional ferrite heads. The thin film technology allows a step of abutting and bonding core halves to be spared, which step provides a dominant influential factor to the yield of magnetic heads fabricated on a mass production base, whereby the magnetic head of a narrow gap and a narrow track can be, on principle, realized effectively.
When the thin film magnetic head for VTR having a track width of several tens .mu.m is to be manufactured through the thin film technique, the magnetic thin films of the materials described above are not suited for realizing the magnetic head of high performances, because of low electric resistivity of these materials, involving a significantly large eddy current loss in the processing signals of a high frequency band. For example, when a magnetic head for VTR destined to deal with signals of MHz in frequency is to be realized with the magnetic core thereof being constituted by a thin film of Sendust, the film thickness has to be smaller than 10 .mu.m and should preferably be smaller than 5 .mu.m in view of the eddy current loss which would otherwise occur in the above frequency band. As the consequence, it is impossible to realize the high performance magnetic head having the track width of several tens .mu.m with the structure of a single thin film layer.
In the light of the situations mentioned above, a head structure in which a number of thin films are laminated has heretofore been adopted. However, in the hitherto known multi-layer thin film magnetic head, a inter-layer insulation film interposed between the magnetic laminar films extends in parallel with the magnetic gap, and a portion of the insulation film remains unremoved even after useless portions of the core have been polished away and operates as an additional magnetic gap (termed the pseudo-magnetic gap), to a great disadvantage, as will hereinafter be described in detail.